This invention pertains to solar cells and, more particularly, to a method for manufacturing photovoltaic devices.
Solar cells are useful to convert solar energy to electricity. Solar cells, the central components of a photovoltaic module, are very fragile. Although the support provided by a substrate such as glass or some other inflexible material may prevent bending and breakage, an encapsulation method is useful not only to provide protection by surrounding the cells but also to serve as a reliable method of attachment to the substrate. The encapsulating material, in addition to offering cost-effective performance should provide the following characteristics: ease of handling in module production; fast processing at temperatures not exceeding the tolerance of other module components, and free of bubbles and voids; potential for automation; high light-transmission; prolonged outdoor exposure capability and thermal stability; protection of the cells against mechanical damage from any outdoor environment; electrical isolation; minimal creep during thermal cycling; and low modulus to absorb stresses due to the differential thermal expansion of module components.
Solar cells and their electrical interconnections are typically covered with plastic and glass to ecologically protect the solar cells and interconnects from environmentally degrading as a result of humidity, pollution, wind, snow, and ice. As mentioned above, the glass and plastic should be free of air bubbles, pin holes, and voids which detract from the appearance of the photovoltaic device and may cause delamination and cell cracking. Solar cells can be used in glass modules, for solar vehicle roofs, architectural glass, facades and other photovoltaic devices.
Glass and automobile manufacturers are generally well equipped to manufacture, install and handle glass panes but are not generally well equipped to produce and assemble solar cells. For reasons of economy and efficiency, it is preferred to manufacture, align, and electrically connect solar cells at the solar manufacturing facility where there is appropriate equipment and skilled personnel for this purpose. The interconnected solar cells can then be transported to glass plants or vehicle factories for assembly of the glass panes since glass panes are heavy and expensive to ship to solar manufacturing facilities. Solar cells and soldered electrical interconnects are, however, fragile and tend to break when shipped loosely or unprotected.
It is, therefore, desirable to provide an improved process to manufacture photovoltaic devices which overcome most, if not all, of the preceding problems.